Does compressing a PDF reduce quality?

The Screen preset reduces image resolution, which may reduce quality slightly. The Printer and Prepress presets maintain high quality with less compression. For documents without images, quality is unaffected.

Is my PDF safe? Does it get uploaded anywhere?

Your PDF never leaves your device. All processing happens entirely in your browser using pdf-lib and PDF.js. No server, no upload, no data collection.

Can I compress multiple PDFs at once?

Yes! Use the Batch tab to upload up to 20 PDFs and compress them all simultaneously with the same settings.

Can I merge multiple PDFs into one?

Yes. Use the Merge tab, upload multiple PDFs, arrange the order by dragging, then click Merge to combine them into a single PDF.

Compress PDF Online Free — Reduce PDF Size Without Losing Quality

PDF Guides & Best Practices

Learn everything about PDF compression, security, and optimization

COMPRESSION

How to Compress a PDF Without Losing Quality

The right compression preset makes all the difference. Learn when to use Screen vs Printer presets, and why stripping metadata alone can save 200KB+...

Read guide → 2025-12-01

PRIVACY

What's Hidden Inside Your PDF — The Metadata Problem

PDFs contain hidden data: your name, organization, editing history, software version, and sometimes your computer's username. Here's how to strip it all...

Read guide → 2025-11-20

PRODUCTIVITY

Merge vs Split PDFs: When to Use Each

Merging PDFs is great for reports and portfolios. Splitting is perfect for extracting invoices from bulk statements. This guide shows the right approach for every scenario...

Read guide → 2025-11-10

SECURITY

PDF Password Protection: User vs Owner Password Explained

Most people don't know PDFs support two separate passwords. The user password controls opening; the owner password controls editing and printing. Here's the difference...

Read guide → 2025-10-28

WEB PERFORMANCE

Optimizing PDFs for Web — Fast Web View & File Size

PDFs on websites load poorly when not optimized. "Fast Web View" (linearization) lets PDFs load page-by-page. Learn to reduce PDF size for faster website loads...

Read guide → 2025-10-15

PRODUCTIVITY

Batch Processing 20 PDFs in 30 Seconds — How It Works

Our batch mode compresses up to 20 PDFs simultaneously in your browser. No queues, no waiting. Here's how browser-based parallel PDF processing works...

Read guide → 2025-10-01

Frequently Asked Questions

How much can I compress a PDF? ▼

Results vary by content. PDFs with many high-resolution images can be reduced by 50–90%. Text-only PDFs typically reduce by 10–30%. Scanned PDFs reduce by 20–60%. Use Screen preset for maximum compression.

Does compressing a PDF reduce its quality? ▼

The Screen preset reduces image resolution — fine for web viewing but not professional printing. The Printer (300 DPI) and Prepress (max quality) presets maintain visual quality. For text-only PDFs, all presets preserve 100% quality.

Is my PDF uploaded to any server? ▼

Never. All processing happens in your browser using pdf-lib and PDF.js — open source JavaScript libraries. Your file never leaves your device. This means it works offline too, after the page initially loads.

Can I compress password-protected PDFs? ▼

Yes, if you know the password. Use the Protect tab to unlock the PDF first (enter the current password), then compress the unlocked version. If you don't know the password, the file cannot be processed.

What's the difference between merging and appending PDFs? ▼

Merging combines multiple PDFs into one document while preserving all pages in order. Appending adds pages to an existing PDF. Our Merge tool lets you drag to reorder PDFs before combining them.

Can I extract specific pages from a PDF? ▼

Yes. Use the Split tab and select "Page Range" mode. Enter ranges like "1-3, 5, 8-10" to extract exactly those pages as a new PDF. You can also split every page into individual files or split into equal N-page chunks.

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